Apparatus for igniting and operating gaseous discharge devices



Nov. 18, 1958 A. E. FEINBERG 2,861,217

I APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES FiledAug. 17. 1954 2 Sheets-Sheet l F'l L AH EMT wmnmcag IL .2. ll 1 1 Z g 192, 21 f7 :5 i F5 e i fw/vee g Nov. 18, 1958 A. E. FEINBERG APPARATUS FORIGNITING AND OPERATING GASEOUS DISCHARGE DEVICES 2 Sheets-Sheet 2 FiledAug. 17. 1954 NNN N O E:

N WN United States APPARATUS FOR IGNITIN G AND OPERATING GASEOUSDISCHARGE DEVICES Albert E. Feinberg, Chicago, Ill., assignor to AdvanceTransformer Co., Chicago, 111., a corporation of Illinois This inventionrelates generally to apparatus for startmg and operating gaseousdischarge devices, and more particularly is concerned with suchapparatus intended for use with fluorescent lamps for lighting.

In recent years fluorescent lighting has developed along lines intendedto increase lighting elficiency from the standpoint of size of lamp andelectrical requirements by way of quantity of copper and steel; tolengthen lamp life and keep operating temperatures low. Quite importanthas also been the problem of keeping line power factor close to unity.The first practical hot cathode fluorescent lamps used starters. Theinitial high voltage ignition pulse was obtained by breaking a circuithaving current flowing through an inductance, and in some cases,transformation was used. The starter provided a short circuit path sothat current initially flowed through the lamp filaments to produceclouds of electrons and thereby enable the ignition of the lamps. Onceignition occurred, the starter switched open by some means, and thelower operating voltage appeared across the lamps with current flowingfrom a hot spot on one cathode to another such spot on the othercathode. Such structures had various disadvantages. For example, astarter freezing closed permitted continuous flow of current through thefilaments which were unable to carry continuous current and hence burnedout. Starters also required additional connections and sockets, andfrequent replacement. Faulty starters resulted in flickering lamps.Principally, there was a considerable wait between energizing thecircuit and illumination.

Then came the so-called instant-start lamp with its leaky ballast. Thelamps were constructed to utilize high voltages and were started bybrute force there being a minimum of current flow prior to ignition.Once current commenced flowing, the leakage reactance of the ballastdropped the voltage to the operating value. This apparatus haddisadvantages in that high voltages were used, and lamp life wasrelatively low because of the stresses to which the same was subjected.

More recently there has been developed the so-called rapid start lampwhich does not start as quickly as the instant-start lamps, but which iscertainly faster starting than starter-operated lamps. The rapid startlamp utilizes filaments in the lamp ends which not only carry currentduring starting, but which also carry current during operation. Throughsuitable construction not necessary to the description of thisinvention, there are no deleterious effects due to the constant flow ofcurrent. The voltages are less than those of the instant-start but stillhigh.

In order to supply the current for the filaments it is necessary to havefilament windings operating at relatively low voltages.

This invention is primarily concerned with apparatus for igniting andoperating rapid-start fluorescent lamps, and hence the ballast which isutilized includes filament windings. High voltage lamps obviouslyrequire considerable voltage for ignition in the event that they are 2connected in series. Rapid-start lamps have heretofore been connectedfor series-sequence, that is, seriatim, starting and in this way it isnot necessary to apply a high voltage across two lamps connected inseries, but the voltage is applied to the lamps one at a time. Thus, twolamps are connected in series across an auto-transformer having aprimary and secondary winding and one of the lamps is shunted by acapacitor. I

Considering this type of circuit utilizing 96" T-12 lamps, 540 volts isapplied to the lamps which ignite at about 275 volts. In order toacquire such starting voltages it is necessary that there be a greatnumber of turns in the secondary which increases the reactance, makingit difficult to correct for power factor.

This invention provides a series sequence circuit in which the opencircuit voltages are decreased thereby making it much simpler to correctpower factor.

It is accordingly an important object of the invention to provideapparatus for starting and operating gaseous discharge devices whichwill provide filament voltages for the devices and which will start thedevices seriatim and thereafter operate the same in series at excellentpower factor characteristics.

It is a further object of the invention to accomplish the ignition andoperation of the device through the use of a sequence start circuit ofnovel structure which will have low open circuit voltagecharacteristics.

As an example of the application of the invention to the same type oflamps referred to above, through the use of the novel circuit of theinvention, an open circuit voltage of the order of 425 volts is all thatis required across the primary and secondary combined in order toachieve starting and proper operation. The lamps operate at volts eachso that total drop across the lamps during operation is only 300 volts,in a series circuit.

As an added feature of the invention, for use in combination either withthe circuit of the invention referred to above or in connection with theconventional series sequence start apparatus, means have been devised toincrease themagnetizing current of the primary without in any wayaffecting the total reactance of the series circuit, as an aid incorrecting power factor.

Many additional objects will occur to those skilled in this art, as adescription of certain preferred embodiments et forth hereinafter ismade. Diagrammatic illustrations of said embodiments serve as an aid tocomprehension and explanation of the invention.

In the drawings, the same characters are used throughout the severalfigures to illustrate the same or equivalent parts.

Fig. l is a side elevational view of a transformer of conventionalconstruction for use in connection with apparatus for igniting andoperating so-called rapid start lamps through the use of a sequencestart circuit of a known type.

Fig. l-A shows how the left hand end of the transformer of Fig. l ischanged in accordance with the inven tion to provide a better powerfactor.

Fig. 2 is a circuit diagram of the conventional series sequence startapparatus capable of being used either with the prior art transformer ofFig. l or with the transformer of the invention illustrated in Fig. 1-A.

Fig. 3 is a circuit diagram of apparatus constructed in accordance Withthe invention in which the circuit has certain novel aspects.

Fig. 4 is a side elevational view of a transformer constructed inaccordance with the invention and having the circuit of Fig. 3associated therewith.

Fig. 4-A is a modified form of the transformer of Fig.4.

Fig. 5 is .a modified form of the circuit diagram of Patented Nov. 18,1958,

d Fig. 4 which can be used in connection with the transformer either ofFig. 4 or 4-A.

The problems involved in providing ballasts for rapid star-Llamps arebest.understood, andtheir solutionby means of this invention bestemphasized through a preliminary studyand explanation of the prior artseriessequence startcircuit illustrated-in Figs. 1 and 2. In Fig. 221sin other figures throughout this specification the .usual lines used assymbols to designate iron cores have been. omitted for clarity.

The presently used series-sequence start ballast includes a-primarywinding P, a secondary winding S loosely coupled therewith to provide aleaky transformation and high leakage reactance for ballastingoperation. The primary P and secondary winding S are connected-inauto-transformer arrangement across a pair of lamps connected in series.In Fig. 2 the lamps are designated L -and L tintheorder of ignition. Theleft hand..terminal of the primary winding? is connected by lead to oneside ofthe filament 11 of the lamp L and the right hand terminal of theprimary winding P connects by Way of lead 13 with the left hand terminalof'thesecondary winding 3. The right hand terminal oflther secondarywinding 5' is connected by lead 15 to one side of the right handfilament 17 of the lamp L The right hand filament 19 of the lamp L andthe left hand filament-21 of the lampL are connected by leads 23and24.The primary winding P is connected across asourcev of A. C. voltage S ofa value less than the ignition voltage of either lamp.

Thereis a condenser C across the lamp L connecting fromlead 15- to 23,and a second condenser C in series with. the-windings and lamps in thelead 15. The condenser C is the starting condenser, and the condenser Cis the power factor condenser.

I: have described the basic circuit of the series-sequence ballast. Theoperation is simple. Energizing of the primary winding P induces a highvoltage in the secondary winding S. The combined voltages appear acrossboth lamps, ie. from lead 15 to lead 10, but since the condenser C haspractically no'effect on the circuit and neither does the condenser C arelatively large voltage appears across the lamp L and it ignites. Assoon as current commences to flow in the circuit, the voltage across Cbuilds up to a point where it is sufficient to ignite lamp L Thereafterboth lamps are supplied with current in series.

In order to provide current for the filaments 11, 17, Hand; 21, threefilament windings F F and F are closely coupled with the primary P.Filament winding F connectsby leads and 31 across filament 11.Filament-windingF connects by leads 32 and 33 to leads 23 and 24respectively and thereby provides current to filaments 19 and 21 inparallel. Obviously separate filament windings for filaments 19 and 21can be used as will. be described in connection with Fig. 5. Filamentwinding F connects by leads 34 and 35 to filament 17 and suppliescurrent thereto.

It is understood that in order for the lamps in series to operateproperly there must be a resultant impedance in the operating circuit toballast the lamps and prevent. their burning out due to their negativeresistance characteristics. Accordingly the sum total of reactance dueto the flow of current through the secondary S and primary P isinductive and it is desired to have a-capacitive reactance predominateso that if anything, the current drawn by the apparatus will be leading.Furthermore, leading power factor is more easily cor rectedas will bedescribed. There must be sufficient excessof capacitive reactance in thecircuit (after compensating for the inductive reactance) to give properoperatingcurrent for the lamps.

The total power factor can then be adjusted by drawing magnetizingcurrent from the line, which is induc- 4 tive insofar as the line isconcerned but has little effect upon the total impedance of the circuit.This is done as described in connection with Fig. 1.

There is illustrated a transformer having a laminated iron core 41 ofshell construction and a central winding leg 42 formed of the samelaminations so that when stacked the winding leg will matingly engagewith the shellcore 41. The-elongated core has an abutting connection 43between its l eft hand bridge end 45 and the left hand end of thewinding leg 42. It has an air gap 47 between its right hand bridge end48 and the right hand end of the winding leg42. There is a support point50 on the right hand end ofthewinding leg 42 to size the gap 47. Thegapmay be formed by shaving.

Two windows are formed at opposite ends of the shell core 41, andwindings slipped over the winding leg 42 and properly positioned areadapted to be engaged and retained in said. windows. Thus thereisfermedagwindow 52 which houses the winding P and. theg tilamentwindings, which are preferably wound on top of windingP. There is alsoformed. awindow-54: which accommodates the winding 8.. There is .a shunt56 formed. between the windows and hence. the windings -P;and .S whichhas -,air gaps 57.

T heshnnt 56 provides the leakage reactance which ,en ables the voltageto drop after starting, but ofconrse this has no effect upon opencircuit voltage. Open circuit voltage will govern the number of .turnsinsecondary winding S, the higher the open circuit voltage-the greaterbeing the numbervof turns. Obviously thegreater the number of turns, thehigher will the total circuit reactance be and. the. more capacitivereactance is required to neutralize this reactance and providenthe.total reactance for ballasting. Thus C s value is governed byopencircuit voltage considerations.

Heretofore, it has beenltnown to provide a.;gap';47 Which causesmagnetizing current to be drawn from the line, the effect of which is toadjust power factor because magnetizing current is inductively reactive.But-where the gap 47 is increased the leakage across shunt 56 isincreased, the circuit leakage reactance;is increased,.and thecapacitive reactance. may be inadequate for proper ballastor ifincreased, may seriously decrease total current flow through the lampsand hence lighting efficiency. The physical size of the primary andsecondary windings are practically limited and. saturation efiectsbecome important.

The.achievement of good power. factor is.-a--very difliculttask with theapparatus ofPigs. l andgZ, the'net result usually being acompromise.

I have found that one manner of solying the difT-iculty is .to provide asecond: air gap 60 at theleft hand end of the winding leg 42- i n,placeofjthe joint.43. It may be of any type snchas, that illustrated inFigl-A and includinga-support point 62. ,Adjustment of this air gapenables the primary winding itself; todraw additional magnetizingcurrentwhich has little effect. upon the leakage reactance of thetransformer, and practically no effects upon saturation in the vicinityof the secondary winding S or the t0tal.reactance of the circuit duringoperation. Thus gap 47 is adjusted for bestswave form and leakagereactance, and the remainder of compensation for excess of capacitivereactanceis achieved through adjustment of the gap 60.

Of course, theuse of-a gap adjacent the primary winding P haspractically noefiect. upon the open circuit voltage. This is still high.The circuits and apparatus described hereinafter alleviate thedifficulties of attempting to achieve proper operating current, properstarting voltage, and good line power factor-encountered in the use ofthe, apparatus of Figs. 1 and 2. Basically this is done by decreasingthe open circuit voltage affecting the operating circuit.

In Fig. 3' there is illustratedaballastfor rapid start lamps which ismounted upon the transformer i1- lustrated in Fig. 4. There is a primarywinding P, a first secondary winding S and a second secondary winding SThe windings are connected end to end in the order named, with thewinding S located between the others and forming therewith the junctions71 and 72. One lamp L is connected across the first secondary winding Salone by leads 74 and 76 connected to one side of each of itsfilaments-11 and 19 respectively. There is a condenser C in the lead 74.The second lamp L is connected across all three windings together bymeans of the leads 78 and 80 connected respectively to one side of thefilaments 21 and 17. The primary winding is connected across a source ofA. C. voltage S of a value less than the igniting voltage of the lamps.Note that lead 74 connects to juncture 72 and one side of the sourceconnects to juncture 71. Both leads 76 and 8d connect to the right handterminal of the winding S and the lead 78 as well as the second side ofthe source are both connected to the left hand terminal of the primarywinding P.

The instantaneous voltage sense of the windings is as indicated by thearrows VP, V8 and VS The secondary windings are in voltage oppositionwith respect to a loop containing both windings and defined by all threewindings and the lamp L In the same loop, the primary and secondsecondary windings are in voltage additive relation.

There are three filament windings F F and F connected by leads 82, 83,84, '85, 86 and 87 to the filaments in the lamps. These connections areeasily traced from the drawing. The windings are wound on top of theprimary.

As shown in Fig. 4 the windings are associated with a transformer 70having an elongate shell core 91, a central winding leg 92 and windows93, 94 and 95 housing the respective windings S and S There are shunts98 and 99 between windings with gaps 1% and 101. The left hand end 102of the central winding leg meets the core bridge end 103 in a matingjoint 105 while the right hand end meets the core bridge end 105 in agap 108 for the same purpose as the gap 47.

The operation of the device is somewhat as described in my Patent No.2,558,293. Upon energization of the primary .winding P, high voltagesare induced in the secondaries S and S Total voltage across lamp L isinsufficient to ignite the lamp because of the bucking effect of thevoltage of S but the voltage of S appearing as it does only across thelamp L is sufiicient in and of itself to ignite the lamp. Firstsecondary winding S is formed of a large number of turns of very finewire because after ignition of the lamp L practically no current flowsthrough this winding. Once current flows through S there is a quadraturevoltage component additive to the voltages of S and -P so that now,after ignition of L there is sufficient voltage across lamp L to igniteit. After ignition, and because of the isolation of the winding Sthrough the use of the shunt 98, very high leakage reactance forces themajor flow of current to be through the lamps and secondary winding S inseries, substantially lay-passing the winding S The open circuit voltageoccurring across the principal windings in the operating circuit (whichgoverns the total reactance of the circuit) is very low. Hence, S isformed of a small number of turns, and the value of C need not be verygreat. The magnetizing current required of the line can much easier beobtained by adjustment of the gap 108 and the desired balance easilyreached. I have also found that additional magnetizing current can bedrawn through the addition of a gap 110 at the left hand end of the coreas shown in Fig. 4A if required without causing any difiiculties. Itwill be noted that there is never a problem of too little inductivereactance in 5 because even the minute current in S through the largenumber of turns provides a flexible method of adjusting total circuitinductive reactance.

Fig. 5 is an illustration of amodified form of the circuit of Fig. 3.

In this circuit, the lamps L and L are respectively connected across theprimary and first secondary windings combined and across the secondariescombined. In other words, the left'hand terminal of the primary windingP is connected by lead to one .side of the filament 11 of the lamp Lwhile its right hand terminal and the left hand terminal of the windingS meet to form junction 71. The right hand terminal of the firstsecondary winding S meets the left hand terminal of the second secondarywinding S in the junction and this junction is connected by the lead 121to one side of the filament 19 of the lamp L The capacitor C is inseries with the lamp L Note that the primary winding is connected acrossa source S of A. C. voltage less than the igniting voltage of either ofthe lamps. The right hand terminal of the second secondary winding S isconnected by lead 122 to one side of the filament 17 of the lamp' Lwhile the junction '71 is connected by the lead 123 to the otherfilament 21.

Note that the windings are connected one after the other, i. e., end toend with the first secondary winding S between the other two and commonto both lamp loops. The secondary windings have their instantaneousvoltages buckingthat is to say, on open circuit V8 and VS are opposed.The instantaneous open circuit voltage sense of the primary winding Preenforces the voltage of S The primary voltage sense is indicated bythe arrow VP. Because of this the voltages which occur at open circuitare very low. Especially the voltages which are expected to be obtainedfrom P and from S This means that the number of turns is low and thereactance during operation is also low.

There are four filament windings F F F and F all wound on top of theprimary winding P and in the same window, it being practical to use thetransformer illustrated in Figs. 4 and 4A for mounting the windings ofthis modified form. These filament windings provide constant currentflow through the filaments of the lamps and provide the initial cloud ofelectrons necessary to start the lamps, as Well as emission duringoperation to keep operating voltages low and the discharge stable.Filament windings are connected as follows: F by leads 131 and 132 tofilament 11; F by leads 133 and 134 to filament 19; F by leads 135 and136 to filament 17; and F by leads 137 and 138 to filament 21. It willbe seen that each filament has its separate winding, instead of usingone winding for two filaments as illustrated in other embodiments.

Operation of the apparatus is as described in the patent hereinabovereferred to. The starting voltage produced across the lamp L by thecombined primary winding voltage and first secondary voltage is highenough to ignite the lamp L The initial voltage appearing across thelamp L is very low and certainly too low to ignite the lamp because thevoltages of the two windings across which the lamp L is connected areopposed. S is a very high voltage winding made upof a large number ofturns of fine wire. Once lamp L has ignited there will be a flow ofcurrent in the winding S and the resulting voltage is so changed inreactive character as to provide a quadrature component which nowreenforces the voltage of the winding S and raises the same an amountsufficient to cause ignition of the lamp L Thereafter, with both lampslit, the reactance of the winding S is so great, especially because ofthe large shunt between it and the remainder of the windings, thatcurrent flows in substantially a series circuit through the lamps andthe second secondary winding S The power factor is controlled by thecondenser C and the side of the end gap 108. The inductive reactance ofthe winding S has no adverse effect upon the ease of adjustment of powerfactor because of the extremely low current flowing in the windingduring operation.

It has been found that the use of filament windings in combination. withcircuits 'of.- the .=type illustrated. in Figs. 3 to 5 do not raise thesame problems asin. other series sequence start circuits,:because, sincethe: basic operating circuits have so little inductive reactance, theadditional drain of current is not important. In a circuit wherethereactance of necessity caused by reason of initially required high opencircuit voltages is. alsohigh, and adjustmenttor power factor isdiflicult, even the added drain-from the primary of filament windingsincreases the difficulty of balance. In this invention, as described inconnection with Figs. 3 to 5 because of the lowopen-circuit voltages,filament windings are no problem atall.

It -is feltthat the invention has been fully described and setforth.hereinabove such that=one skilled in the ballastartcouldconstructthestructures and practice the invention. This isespecially true in view of the well-known characteristicsand thewidespread usage of the circuits of thepatentuhereinabove referred to.

I claim:

1. Apparatus for igniting and operating rapid start tluorescenttlightingdevices with suitable regulation after operation commences; whichvcomprises, a pair of rapid startdeviceseach having end filaments, asource of A. C. voltageofrelatively low value, an elongate iron coreshell of rectangular structure and having end bridging portions, acentral winding leg matingly engaged between the end. bridging portionsand having -a-transformer formed-Lot primary, first secondary, andsecond secondary windingsrnounted thereon, thewindings being physicallyseparated by high reluctance magnetic shunts, the primary beingbetweenthe other two windings, and an end gap between the windingleg-and the bridging portion adjacent the second secondary winding, aplurality of filament windings. alllmountedin closecoupled relation tothe primarywinding and connectedfto the filaments to continuouslyenergize the same, the primary and. secondary windings beingconnectedend to end, with the secondaries bucking one another considering an opencircuit loop containing the primaryand both. secondary windings inseries, a condenser in series with one device, and together therewithconnected across a part of the transformer excluding the secondsecondary winding but including atle'ast the first secondary winding,the second device being. connected across a part of the transformerincluding at .least both. secondary windings.

2.1Apparatus as described in claim 1 inwhich there is another and gapbetween. the windingzleg and the opposite bridgingportionadjacent thefirstsecondary winding.

3; Apparatusfor igniting and operating gaseous dischargedevices withsuitable regulation which comprises a.pair=of.- gaseous dischargedevices having filaments in oppositeends thereof, a source of A. C.voltage of value lessthan the igniting voltage of either device, anelongateferromagnetic core of shell type having a central win-ding: legtherein, ,a. transformer comprisinga primary winding and. twosecondarywindings. said. primary winds ing connected acrosslthe source,therwingjiugsibeingt COIL- nected end to .end with the connectionbetweeni secondaries providing a junction,v andthe-\secondariesebeing.in.open; circuit voltage opposed; relationshipwith respecttoa loop,

containing, all windings, theprimary and;secondar y,wind ings beingmounted on saidwinding, leg. with the primary winding in the centerandlhigh reluctanceshunts between it and the other t-wo windings,,a leadextending from said junction to one, side of a filament ofthe first ofsaid gaseous discharge devices, one side of the second.

filament of said first gaseous discharge device beingconnected to a partof said transformer to have at least the voltage of said firstsecondarynwinding applied thereto on open circuit, a condenser in serieswith. said first gaseous discharge device in aloop includingtthe said:first secondary winding, therfirst side of each of the filaments onopposite ends of thetsecond. gaseous discharge device being connected toparts of said transformer other than said junction for applying thevoltages of windings including at leastboth secondaries across the same,the discharge devicesbeing ignited in the order named by virtue of aphase reversal in the voltage of said first secondary Winding afterignition of the first gaseous discharge device, a plurality of filamentwindings closely coupled with the primary winding and connected to.continuously supply current to said filaments through the. terminals ofsaid filaments, andga non-magnetic gap at the end of said centralwinding leg.

4. Apparatus as claimed in claim 3 in which there is a second gap at theother end of said central winding leg.

5. Apparatus as. claimed in claim 4 in which the second secondarywinding is connected. between the primary and first secondarywindings,.and thesaid. first gaseous discharge device and said condenserare connected inseries together across: said first secondary winding,and the second gaseous discharge device is connected across primary andboth secondary windings together.

6. Apparatus as claimed in claim 4 in which the first secondary windingis connected between the primary and second secondary windings, and thesaid first gaseous discharge device and said condenser are connected inseries together across the primary and first secondary windings, and thesecond gaseous discharge device is connected across both secondarywindings.

References Cited in the file of this patent UNITED STATESPATENTS2,504,549 Lemmers .Apr.. 18, 1950 2,510,209 Bridges June 6, 19502,585,963 Ranney Feb. 19, 1952 2,611,885 Bridges Sept. 23, 19522,683,240 Strange July 6, 1954

